add volume test for 2nd order tets in UNV format, too

- cleaned up the octree code (renamed some files, added copyright
  notices, indented everything)

- backported JF's doc from the texinfo file into the c++ code (the
  documentation is actually generated automatically by Gmsh with
  "gmsh -doc"!)

- replaced nPoints with nPointsU and nPointsV in CutGrid

- fixed a couple of printfs + removed some unused variables

- define edges_XXX only once

- draw slightly larger/visible mesh points

- make t1.geo/t2.geo faster

- Added nice little buttons in the mesh menu to choose between 1st and
2nd order interactively

- Added 2nd order mesh stats in the GUI

- converted 2D_Recombine and SecondOrder to the EdgesContainer class
- removed the quadrangle hak and the ugly EdgesInVolume global from 3D_Coherence

- Fixed second order mesh generation in 3D (on simplices only at the moment).

- In prevision of the extension to hexas, prisms and pyramids, all elements
are now derived from a new Element base class, which will be used in the
generalization of Edge/EdgesContainer in the future.

Improved xytouv() and xyztouv() by trying different initial guesses in the
newton algo (before relaxing). Should be more robust than what we did before.

added new constructor with no arguments in prevision of Degre2 cleanup

Fixed computation of vertex->u param in curve extrusion

make parser && make depend

acos->myacos

- Simplified the bounding box computation. It is now computed as
follows (after each include/merge/open):

1. If there is a geometry (i.e., at least one geometrical point), the
bounding box is taken as the box enclosing all the geometrical points;

2. If there is no geometry but there is a mesh (i.e., at least one
mesh vertex), the bounding box is taken as the box enclosing all the
mesh vertices;

3. If there is no geometry and no mesh, but there are some
post-processing views, the bounding box is taken as the box enclosing
all the primitives of the last post-processing view.

This should fix the weird things that sometimes happen when we animate
scenes that do not contain any geometrical entities.

- Deprecated MergeWithBoundingBox()

- Removed Replot()

- Removed the "Last_NumberOfPoints" hack in the parser

- Removed CTX.expose

fix gcc warning

pretty print

New raster ("bitmap") PS/EPS/PDF output

I forgot to commit these last week: it's just the beginning of some
cleanup of the old 2D algorithm (removed non-functional voronoi
insertion, fixed a couple of memory leaks, added some comments, etc.)

And more airplane work!

- merged STL patch from Nicolas Tardieu. This patch permits to
  create an real elementary surface for each STL face. Until
  we have some code to directly remesh the STL data (which would
  be much nicer and cheaper), this is very useful. We can finally
  use STL representations to create meshable volume models.
  Thanks Nicolas !

- new option to color the mesh by physical entities (if an element
  belongs to multiple physicals, we use the first one)

- additional cleanup of the mesh drawing code

- big cleanup of the geometry creation section in the parser:

  * removed horrible Geo/DataBase.cpp
  * fixed all List-related memory leaks (a lot!)
  * added tests to check if we don't try to recreate existing
    entities (this should prevent many weird bugs due to incorrect
    input files)

- fixed LineLoop/EdgeLoop memory leaks

- many small fixes all over the place

Update copyright notice

Previous commit was completely wrong. Need to think a little more
about this problem.

increment the factor more slowly

Better edge swapping for non-recombined extruded meshes

Removed extra arg for Init_Mesh

Add a couple of 'else if's

new "Delete All;" command + only warn when reloading duplicate geometry
points.

some more cleanups

List_Replace->List_Insert

Handle multiple physicals for single elementary

New MSH file format, version 2.0.

********************************************************
************ Please send me your comments **************
********************************************************

Small changes for skeletton of new mesh format

Added support to visualize mesh partitions. The partition info is currently
set as the physical entity number in the MSH file, but it would be trivial
to change it to something else (e.g., as soon as we generalize the MSH
format to take arbitrary number of tags per element).

Explicitly say that the mesh will be incorrect if the swapping failed

Fixed one more bug for degenerate, non-recombined extrusions, that could
lead to duplicate elements.

Fix seg fault in Read_SMS

Fixed degenrate tets generation (oops!)

- new DecomposeInSimplex plugin
- new "Combine Views" command in the parser
- cleaned up View::tranform and View::smooth (+small bug fix for SLs)
- better check for transparency sorting
- make depend
- new View.AlphaChannel option to change the transparency
  globally for a given view (instead of having to change the colormap
  by hand every time)

With all the above, we can now generate very nice (and correct)
transparent iso-surfaces:

Merge "../tutorial/view3.pos";

minIso = 0;
maxIso = 2;
nbIso = 7;

Plugin(CutMap).iView = 0;

For i In {1:nbIso}
  Plugin(CutMap).A = (maxIso-minIso)/nbIso * i;
  Plugin(CutMap).Run;
EndFor

Delete View[0];
Combine Views;

For i In {1:nbIso}
  Delete View[0];
EndFor

Plugin(DecomposeInSimplex).iView = 0;
Plugin(DecomposeInSimplex).Run;

View[0].AlphaChannel = 0.6;